3 kva inverters and batteries

[Isetech]

What are your thoughts on the small 3 kva unit with 2 x 100 amp/hr batteries ?

I have noticed more and more of them mounted next to the DB with the batteries just open on the floor below the inverter.

In most cases, they are wired directly form the inverter straight into the DB, no indicator lights, no fuse protection on the batteries.

Would they be regarded and plug and play, I would think not because once they are connected to the DB circuit breakers and not plugged into a wall socket they become part of the elctrical installation and would require a COC.

The batteries left open on the floor start creating a few other challenges. One being that the ones supplied with the inverter are not deep cycle leisure batteries, designed with a thick base so that they can be left on a concrete floor.

Some might say that they release a combination of hydrogen and oxygen while charging, some say they dont, because they are gel or AGM. Even if they were deep cycle lead acid, at what point would they become a problem? If they were a problem then we would have a huge problem, because of all the mobile units already sold.

Maybe the fact that the mobile unit is inside a metal enclosure, would make it a safer option.

At what point does the location the units are installed become a too confined for the units?

Something to think about

[Isetech]

To put a spanner in the works, most of these batteries are sealed lead acid batteries, VRLA, gel or AGM, maintenance free batteries.

In reality they should not release any form of gas or such a small amount that it wouldnt even be considered a threat, or deem the location to be classified as a hazardous location.

My 600 watt inverter has been in a cupboard in my TV room since ellies introduced the first mobile inverter back when load shedding started, I have replaced more batteries than I can remember, that is long long it has been enclosed in a confined space in the cupboard. Back in the day it was a Deltec 105 amp/hr and more recently the enertec leisure premium FLA battery.

[Justloadit]

Seems every one has been lucky so far.

I have had a situation, in which over night a gel 35A battery failed in a small inverter which has a constant voltage and current limited battery charger, not sure what happened to the battery as the charger did not fail, but the gel in the battery boiled, the plastic bulged and cracked, and released some horrible smell into the air and liquid came out the battery.
Luckily when I came in I smelled this and was able to identify the issue. Not sure what would have happened if it was not detected in time.

I suspect that one of the cells failed as a short circuit. In most cases with lead acid, the cell fails where the cell capacity changes, which causes the terminal voltage to raise quickly shutting off the charger.

[Isetech]

Seems every one has been lucky so far.

I have had a situation, in which over night a gel 35A battery failed in a small inverter which has a constant voltage and current limited battery charger, not sure what happened to the battery as the charger did not fail, but the gel in the battery boiled, the plastic bulged and cracked, and released some horrible smell into the air and liquid came out the battery.
Luckily when I came in I smelled this and was able to identify the issue. Not sure what would have happened if it was not detected in time.

I suspect that one of the cells failed as a short circuit. In most cases with lead acid, the cell fails where the cell capacity changes, which causes the terminal voltage to raise quickly shutting off the charger.

This is very common.

This is why we makes sure the date of installation is recorded, and monitor the site charge cycles and temperature of the batteries, via the remote viewing. We have found that this generally happens around 3 year and 6 months after installation, if the system is permanently connected and monitored.

The last batch of 16 batteries we replaced, we identified the issue within 2 hours they were replaced.

[Isetech]

When people say, "my battery is still working 5 years later" I just smile.

You will smell a rotten egg smell as soon as the batteries begin to boil.